The present invention relates to a multicast routing method and apparatus for routing a multicast packet and more particularly to a multicast routing method and apparatus for realizing multicast communication between an IPv4 terminal using IPv4 (Internet Protocol version 4) as a communication protocol and an IPv6 terminal using IPv6 (Internet Protocol version 6) as a communication protocol.
In recent years, it has been feared that the 32-bit address space on networks provided by the IPv4, if left alone, will soon be used up. To avoid the possible exhaustion of the address space, the IPv6, the next version of IPv4, has been developed and is drawing attention as a means for networking new terminals (for example, mobile IP terminals).
An example method for establishing communication between IPv4 terminals based on the IPv4 protocol and IPv6 terminals based on the IPv6 protocol is a technique disclosed in Japanese Patent Unexamined Publication No. 10-136052. The Japanese Patent Unexamined Publication No. 10-136052 describes that a DNS (Domain Name System) protocol extension technology incorporated into a device installed in a communication path generates an IP address conversion table that manages the correspondence between IPv4 addresses and IPv6 addresses and, based on the IP address conversion table, performs conversion between an IPv4 header and an IPv6 header. The use of this technology disclosed in the official gazette enables communication between IPv4 terminals and IPv6 terminals.